Dynamic graphs evolve over time through edge births, deaths, and node arrivals/departures. Real-world examples include social networks (friendships form and dissolve), citation graphs (papers accumulate links), and biological networks (protein interactions change with cell state). Preferential attachment (Barabási-Albert model): new edges attach to high-degree nodes with probability proportional to degree, generating scale-free networks with power-law degree distributions P(k) ~ k^(-γ). Edge age is shown by color — fresh edges glow bright gold, old edges fade to blue before dying.